Decoding Season 3 Motor – What changed from previous seasons?

TECH TALK

Posted on: 27 October, 2017

Every season comes with its highs and lows. Season 3 of Formula E - the world’s first fully electric racing series - was no different and it did produce some memorable moments for us. We recorded our best-ever season, finishing third. We secured our first race win too.

Three seasons so far and each year, we’ve done better than the last. How do we manage that?

The passion is omnipresent and when you throw high-ended engineering into the mix, the duo is hard to beat.

Every season also comes with its fair deal of changes. Season 3 saw us drop the McLaren motor and move to Italian tech supplier Magneti Marelli.

What changed? How much of an impact did it have on our season? Our Formula E Chief Engineer Vinit Patel was on hand to get to the bottom of it all.

What changed?

"Our season two used an evolution of existing technology from McLaren, driven by time constraints rather than outright performance targets. For season three, we started with a blank piece of paper. The process began even before the first race of season two. The FIA is actually quite open with regards to the future regulations. The governing rules are fairly basic, with some capacitance and voltage limitations and not really much else except the physical envelope of the standardised car dimensions."

"We split the requirements into three main areas; transmission, motor and control electronics. We carried out a principles-led analysis of what we needed from the motor and inverter to get the best result on track. This evolved from a basic spreadsheet to thousands of laps of simulation to test variables such as mass, centre of gravity, RPM range, torque range, thermal characteristics and efficiency maps. Eventually, we were able to hone in on some key requirements, and ultimately a shortlist of suppliers that had technology that could meet those requirements."

The challenge

"The main challenge in designing a Formula E racing car motor is finding the best compromise between packaging requirements, weight, efficiency and dynamic performance. Many iterations were worked through with our partners at Magneti Marelli before a suitably optimised design was agreed."

Different approach for regenerative braking

"Regen requirements need full analysis and simulation to account for the increased duty cycle on the motor and other powertrain components, especially reverse forces not seen in normal motorsport applications. This means it is vital to account for it to correctly life the components and specify correct materials and dimensions of the pack."

Design principles not very different to F1 and World Endurance Championship

"The design principles are the same: understand the application and simulate to know your end requirements. So while F1 has a more complex energy management structure with the current turbo and ERS systems, the design process is not much different as long as the understanding is in place."

Technology advancement

"Formula E is a sport and, as such, it means you look for technology to give the competitive edge and we are willing to take more risks or pay higher costs for this advantage. For motors there is a lot of scope for improvement in materials, motor design techniques, new magnetic technologies and design optimisation. All this leads to motors with higher potential performance, lower weight and ultimately higher efficiency. Formula E allows an arena for advancing these areas at a faster pace than the product- and business-orientated world because performance comes first, not financial profits, in racing."

Timeline

September 2015: Our analysis process begins December 2015: The specification is fixed April 2016: The first prototype runs on the test bench May 2016: The prototype runs in the development car

We completed nearly 4000km of track testing with the new powertrain over a combination of private and public test days, equivalent to two full seasons of racing. That reliability was clearly carried through to the racing season.

Not long to go for Season 4 where we will look to reach even greater heights.